PERISSODACTYLA, ARTIODACTYLA, AFROTHERIA

Transcription

1 PERISSODACTYLA, ARTIODACTYLA, AFROTHERIA Know the terms in bold type. For laboratory, be able to identify the key characteristics present in the available specimens. Other characters will be useful to know for lecture. UNGULATA Ungulates are mammals having hooves. To lengthen the legs, ungulates evolved unguiligrade locomotion: they walk on the modified nails (hooves) of their toes. Perissodactyls walk either on three toes or on one toe. Terrestrial artiodactyls walk on two toes or four toes (hippos). Whales (Cetacea) are descended from terrestrial artiodactyls. Order Perissodactyla: Odd-toed ungulates A. digit 3 is the main weight bearer (mesaxonic) B. femur with third trochanter C. astragalus with pulley-like surface above for movable articulation with tibia, flattened below 1. Family Equidae--horses, asses, zebras A. Foot with one functional digit (monodactyl) B. orbit separated from temporal fossa by postorbital bar C. dental formula 3/3, 0-1/0-1, 3-4/3, 3/3 D. canines, when present, are relatively small and located in diastema between incisors and premolars E. cheek teeth hypsodont, with complex ridges 2. Family Tapiridae A. forefoot with four digits, hindfoot with three B. retracted nasals (note they are above the eye) for snout that is modified into a short, movable proboscis C. orbit confluent with temporal fossa D. cheek teeth brachyodont, with two transverse crests E. dental formula 3/3, 1/1, 4/3-4, 3/3 3. Family Rhinocerotidae

2 OrderArtiodactyla: Even-toed ungulates A. Over a hundred living terrestrial species, including sheep, goats, camels, pigs, cows, deer, & antelopes. B. Cetaceans (whales and dolphins) are highly derived artiodactyls Characters A. digits 3 and 4 subequal (paraxonic limb structure) B. double-pully astragalus (rounded articular surface on both ends) C. Foot posture digitigrade or unguligrade Suborder SUINA a. unfused metapodials, no antlers or horns b. bunodont cheek teeth; tusk-like canines c. simple 2-3 chambered stomach 1. Family Suidae--pigs, hogs A. skull long and low; snout elongate and flattened at end B. dental formula 1-3/1-3, 1/1, 2-4/2-4, 3/3 C. warthogs lose teeth with age, a. an old adult can be 0/0, 1/1, 0/0, 1/1 D. upper canines curve upward and/or outward; lowers curve outward E. skull long and low; snout elongate and flattened at end F. four toes on each foot 2. Family Tayassuidae (= Dicotylidae)--javelinas or peccaries a. dental formula 2/3, 1/1, 3/3, 3/3 b. upper canines directed downward c. four toes on front foot; three hoofed toes on hind foot [digit 5 is present, but vestigial] d. fewer tail vertebrae than suids e. rump gland

3 SELENODONT ARTIODACTYLS Camelids and ruminants A. enlarged stomach divided into 3 or more chambers (ruminate) B. selenodont cheek teeth C. cannon bone (fused metapodials 3 and 4) is present D. upper incisors reduced or missing E. postorbital bar complete 3. Family Camelidae--camels, llamas, vicuñas A. Secondarily digitigrade B. canon bone present but not fused distally C. dental formula 1/3, 1/1, 3-2/2-1, 3/3 D. Lower incisors spatulate, procumbent Suborder Ruminantia A. no upper incisors B. incisiform lower canine (see syllabus) C. horns (hollow bony core that is permanent) or antlers (solid bony core that is shed) usually present in at least males D. four chambered stomach (3 in tragulids) E. Unguiligrade 4. Family Cervidae--deer, elk, moose a. antlers usually complex (forked); solid bony core nourished from epidermal layer of velvet; usually in males only b. side toes (dew claws) present, but small and non-functional c. upper canines present in some taxa. Usually small and rounded if present. Large in Chinese water deer (b in figure to right below) d. lacrimal depression (rf and ap below left) is present. e. two lacrimal foramina present at front edge of or outside orbit (arrow, below right) Horns in bovid (above) and antilocaprid (middle). Antlers in cervid (below)

4 5. Family Giraffidae--giraffe, okapi. a. horns composed of outgrowths of frontals that start as a distinct bone (ossicone) b. horns present in both sexes, unbranched, covered with skin, non-deciduous 6. Family Antilocapridae pronghorn a. Horn forked with small anterior projection consists of permanent bony core projecting from frontal bone and an epidermal horny sheath. b. Sheath is shed annually; females often hornless and frequently lack prongs c. hypsodont teeth d. two toes on each foot 7. Family Bovidae--cattle, sheep, goats, antelope, and allies a. horns with keratinous sheath always present in males, variable in females, unbranched, sheath and bony core non-deciduous b. four toes usually present on each foot. Side toes (dew claws) are small and non-functional (occasionally absent) Suborder CETACEA A. fusiform body with shortened neck and elongate tail B. tail modified into horizontal flukes C. paddle shaped anterior limbs D. external nares dorsally located 1. Suborder Mysticeti--baleen whales A. Traits A. no teeth, except embryologically B. baleen present 2. Suborder Odontoceti--toothed whales a. Traits teeth present, simple, homodont b. no baleen c. skull generally asymmetrical around the external nares Skeletons of modern mysticete (above) and odontocete (below) whales, illustrating the flipper forelimbs with joint movement only at the shoulder and the loss of hind limbs (remnants of the pelvis are present in mysticetes) A. 11 Families of odontocetes, including

5 a. Family Delphinidae dolphins a) variable traits, b) largest family [17 genera, 34 spp.] Examine the dolphin skull and lower jaw. Locate the nasal frontal, parietal and occipital bones. What features are related to echolocation? AFROTHERIA The Superorder Afrotheria is based on molecular evidence that indicates the relationship of tenrecs, golden moles, elephant shrews, aardvarks, and tethytheres ("Paenungulata" - elephants, sirenians, and hyraxes). Tethytheres and possibly aardvarks had been considered to be ungulates. Order AFROSORICIDA 1. Family Tenrecidae--tenrecs 2. Family Chrysochloridae golden moles Order MACROSCELIDEA elephant shrews 1. Family Macroscelididae a. Skull is similar to Insectivora, Scandentia, and small insectivorous marsupials b. no postorbital bar c. complete auditory bulla d. complete and imperforate zygomatic arch e. heavily perforated palate f. Body size small (17-58 cm) g. body form quadrupedal saltator, hindlimbs much longer than forelimbs h. snout extended into long, movable proboscis Order TUBULIDENTATA aardvarks 2. Family Orycteropidae a. Size medium-large ( cm), pig-like b. Tubular snout, long thin dentary c. no incisors or canines in adults d. 5/5 cheek teeth homodont e. zygomatic arch complete (not like xenarthrans, pholidotes) What is the diet of Orycteropus? What features of the skull and dentition indicate this?

6 Order HYRACOIDEA--hyraxes, conies 1. Family Procaviidae A. medium-sized (marmot-like, rabbit sized) B. dental formula 1/2, 0/0, 4/4, 3/3 C. upper incisors triangular, evergrowing, tusk-like, composed mostly of dentine, with enamel-free posterior surface D. cheek teeth lophodont, relatively simple, becoming progressively more complex from front to back Order SIRENIA sea cows, manatees, dugongs 2. Family Trichechidae manatees A. tail fluke evenly rounded, posterior margin not notched B. nasals high on skull C. premaxilla small, only slightly bent downward D. Upper incisors absent E. Cheek teeth with two transverse crests F. tooth replacement from rear, like elephants, up to 30 teeth 3. Family Dugongidae dugongs A. tail fluke dolphin-like, with pointed lateral projections; posterior margin deeply notched B. premaxilla large, bent sharply downward Order PROBOSCIDEA--elephants 4. Family Elephantidae a. upper incisor evergrowing, tusk-like; composed of dentine b. hypsodont and lophodont cheek teeth, consecutively replaced from rear (only one tooth functional at a time)